The objective of this research is to determine the structure of rubredoxin from D.vulgaris to the highest possible precision and to compare and correlate its properties with those of other rubredoxins. The methods used will be those of single crystal x-ray diffraction. BIBLIOGRAPHIC REFERENCES: Adman, E.T., K.D. Watenpaugh and L.H. Jensen 1975 N-H...S Hydrogen Bonds in P. aerogenese, C. pasteurianum Rubredoxin and Chromatium High Potential Iron Protein. Proc. Nat. Acad. Sci., USA, 72: 4854-4858. Jensen, L.H. 1976 Protein Model Refinement by Fourier and Least-Squares Methods. (In press in Lectures, International Summer School on Crystallographic Computing, Prague, Czechoslovakia, 1975)